Enhanced neural sensitivity to brief changes of happy over angry facial expressions in preschoolers: A fast periodic visual stimulation study

Across childhood, emotion perception from facial expressions has traditionally been studied with event-related potentials (ERP). Here, we explored the novel fast periodic visual stimulation (FPVS) EEG approach to provide information about how brief changes in facial expressions are processed implicitly in young children’s brains. Employing two FPVS tasks for the first time in preschoolers, we examined brain responses to (1) the discrimination of brief changes in facial expressions at maximum intensity and (2) thresholds for discrimination of gradual increasing facial expression intensities. Within a stream of neutral faces at 6 Hz, happy and angry faces were embedded with a frequency of 1.2 Hz. Additionally, children performed an emotion recognition task (ERT). Data was collected in the context of a training study for socio-emotional competencies with typically developing children (N = 74; 5.1(0.9) years; 34 females). FPVS data was collected post-training, where training was included as a controlling factor. Across FPVS tasks, we detected robust expression change responses, particularly with larger responses for happy vs. angry faces in the maximum-intensity task. ERT results paralleled neuronal findings with faster reaction times and higher accuracy rates for happy vs. angry faces. For gradual increases of emotional intensity, we found linear increases in responses across emotions. The majority of the sample showed a significant expression change at 60 % intensity. With its implicit nature, short duration and robustness of individual responses, our results highlight the potential of FPVS in comparison to classical ERP methods to study neuronal mechanisms of emotion perception in preschool samples.